Spatio-temporal Analysis for Extreme Temperature Indices over Levant region

Abstract

The temporal and spatial trends of 16 climate extreme indices based on daily maxi-mum and minimum temperatures during the period 1987–2016 at 28 stations dis-tributed across Israel and Palestine territories in the Levant region were annuallyand seasonally analysed. The nonparametric Man-Kendall test and the Sen's slopeestimator were employed for the trend analysis. Results showed that the region hassignificantly experienced a dominant warming trend for the last three decades, withmore intense changes for minimum temperatures than for maximum. At annualscale, maximum values of minimum temperatures exhibited significant increasingtrends up to 0.68 C/decade. For percentile-based extreme temperature indices,changes detected were more pronounced than those for the absolute extreme tem-perature indices, with 93 and 89% of stations significantly showed increasingtrends in TX90p and TN90p, respectively. The duration and fixed thresholdextreme indices confirmed the trend toward a warming, with the 86% of the sta-tions exhibited significant increasing trends in the annual occurrence of summerdays (SU25) and tropical nights (TR20). Moreover, 57% of stations showed signifi-cant increasing trends in their very summer days (SU30) index. At seasonal scale,the analysis of trends for extreme temperature indices showed intense and broadsignificant increasing trends in all absolute extreme temperature indices. In sum-mer, more than 75% of total stations exhibited significant increasing trends forwarm days and warm nights (TX90p and TN90p). In winter and spring, 71% of thetotal stations also showed significant increasing trends in SU25 index, whereas thepercentage of stations reached 82% in summer and 64% in autumn for significantincreasing trends in TR20 index. Finally, the influence of large-scale circulationpatterns on temperature extremes was examined. The results highlighted the pres-ence of significant correlations between most of the selected extreme temperatureindices and the North Sea-Caspian pattern at annual and seasonal scales.